Some of the comments made by HN participants who posted during the first hour this 2003 article was posted bring up the main point: clinical trials should be informed by prior probabilities. That's why some medical researchers, while not saying that clinical trials are a bad idea, identify the best practice as "science-based medicine" (medicine that takes into account prior probabilities and basic principles of science when evaluating clinical trials) rather than "evidence-based medicine" (which many observers take to be a designation for relying on clinical trials to evaluate treatments). The "About" page on the Science-Based Medicine group blog site puts it well:

http://www.sciencebasedmedicine.org/index.php/about-science-...

"Good science is the best and only way to determine which treatments and products are truly safe and effective. That idea is already formalized in a movement known as evidence-based medicine (EBM). EBM is a vital and positive influence on the practice of medicine, but it has limitations and problems in practice: it often overemphasizes the value of evidence from clinical trials alone, with some unintended consequences, such as taxpayer dollars spent on 'more research' of questionable value. The idea of SBM is not to compete with EBM, but a call to enhance it with a broader view: to answer the question 'what works?' we must give more importance to our cumulative scientific knowledge from all relevant disciplines."

The previous comments posted here mentioning what we can know about falling human bodies from first principles of how free fall in the earth's near gravitational field works, or by experiments with dummies including instruments, or by historical experience with aircraft disasters, correctly point out that randomized controlled trials should be designed with all the relevant science in mind. Further, clinical trials should be designed both to gain knowledge of the effectiveness of varying treatments and to minimize risk to human subjects of treatments (jumping out of an airplane without a parachute, for example, or using acupuncture, for another example) with no strong evidence of effectiveness.

See my all-time favorite link to share in HN comments, LISP hacker and rocket scientist (and now director of research at Google) Peter Norvig's article "Warning Signs in Experimental Design and Interpretation"

http://norvig.com/experiment-design.html

on how to interpret scientific research.

AFTER EDIT: In answer to the question, "Where is the evidence that EBM or SBM helps?", the evidence is all around you, all over the world. I've lived in more than one country, and I have had access to the research library of a major university health sciences center since I was in high school, and the incremental improvements in human lifespan at all ages, young and old, and the reduction in disease burden from all kinds of diseases

http://www.scientificamerican.com/article.cfm?id=longevity-w...

are an outcome caused in large part by better understanding of how to prevent or treat disease, an understanding that comes about from science-based medicine.

The article I just submitted today

http://news.ycombinator.com/item?id=4644708

about systematic reviews of acupuncture research in China illustrates the drawbacks of doing anything but science-based research on human disease prevention and treatment. People can imagine that a lot of speculative treatments work, but the way to demonstrate that one treatment or another works is to investigate it carefully with the underlying science in mind.